Last month, we published reader comments about how much, if any, health information you disclose on the dive shop medical
questionnaire. Most of you say you keep mum. I saw many of the reasons you gave for why as quite valid. Doc Vikingo, a frequent
Undercurrent contributor, does not. Here’s his opinion:
Scuba diving, perceived by much of the non-diving public as risky if not outright dangerous, has avoided government
  meddling to an astonishing degree. Regulation by federal, state and local governments has been avoided largely
  because the dive industry polices itself. This includes common practices like asking divers to complete a medical
  history questionnaire before training or a taking a dive trip. This self-policing has benefited divers by giving them
  freedom to dive whenever, however and with whomever they choose. Much of this is obviously due to divers adhering
  to industry practices. But when it comes to being forthright in completing medical questionnaires, it’s sometimes
  a different story.  
When Undercurrent asked readers about whether they disclose medical conditions to dive operators, a surprising
  number of you replied that you didn’t, for fear of an operator not permitting you to dive. But I’m with much of the
  dive industry and medical experts in believing it’s a mistake not to tell the truth about your health. It could cost you
  your life, and possibly the lives of the buddies and guides you’re diving with.  
The risks are real. For example, Divers Alert Network’s annual report on dive-related accidents and deaths routinely
  indicates that cardiovascular events cause 20 to 30 percent of all fatalities. Moreover, medications like tranquilizers,
  antidepressants and narcotic pain relievers and certain cardiac and respiratory drugs that cause no problems
  topside may act differently at depth, and may combine with or increase nitrogen narcosis, resulting in significantly
  impaired thinking and behavioral control.  
“The Diver’s Responsibility, not the Dive Center’s”  
Consider this tale sent in by an Undercurrent reader about a Bahamas dive he did last June. One of his fellow divers
  was a 68-year-old woman who looked physically fit and at least a decade younger. However, during the first dive,
  one of the divemasters had approached her at 75 feet, motioning for her to ascend a bit but she kept descending. At
  100 feet, the divemaster physically tried to force the woman to ascend but was pushed away. He partially inflated the
  woman’s BCD but she immediately dumped the air through her shoulder valve. Another divemaster then descended
  to 170 feet and could see the woman’s bubble line starting well below his depth. He used the backup tanks suspended
  below the boat to decompress from the extreme depth. The woman’s body was never found.  
Our reader later learned through a mutual acquaintance that the woman had had a minor stroke the month
  before that Bahamas dive. “There has been considerable speculation about the cause of her actions and subsequent
  disappearance,” he wrote us. “While we may never know for certain, the leading theories are that she either got
  nitrogen narcosis at 70 feet, or suffered a stroke and became confused and disoriented. If she had a transient ischemic attack, or TIA, (a ‘warning stroke’ or ‘mini-stroke’ that produces stroke-like symptoms but no lasting damage.)
the month prior, my medical friends indicate it is dubious she would have received a physician’s clearance to
dive. There are generally other underlying medical issues, and a greatly increased risk of suffering another stroke
after a ‘minor’ TIA stroke.”
Out of curiosity, our reader e-mailed PADI and asked about its fitness-to-dive policy. The reply: “While dive
  students are required to complete a medical history questionnaire before participating in any PADI courses, PADI
  diving facilities are not required to medically screen all of their customers. Divers learn during their training that,
  after certification, they must always ensure that they are medically fit for diving before doing so. This is the diver’s
responsibility rather than the dive center’s.” 
  
    | “If divers knowingly conceal their conditions once they know what the
 risks are, it’s not just themselves
 they’re putting at risk . . .”
 | 
Because so many of you readers admit that you are
  untruthful on the medical release, we wondered if dive medicine
  experts did the same, just to avoid the hassle of dealing
  with dive operators who have far less medical knowledge. Ern
  Campbell, M.D., a.k.a. the blogger ScubaDoc, said that even
  if he had a condition he feared may prevent a dive operation
  from taking him on board, he still “would disclose the condition
  to the operator and expect an appropriate explanation
  of any denial to dive.” Dr. Michael Bennett, president of the South Pacific Underwater Medicine Society, told us: “I
  believe the medical risks of diving are real and present a threat to my well-being. Therefore, I would not be selfish
  enough to cheat and put my fellow divers at risk when they might be called upon to save me!”  
Drugs Work Differently Underwater  
Common reader statements we received included, “I’m capable of monitoring my own medical problems” and
  “I don’t pose a danger.” In many cases, such assertions are not accurate. For example, common conditions like
  asthma, diabetes and seizures may appear well-managed but can unexpectedly and rapidly spiral out of control.
  When they do so underwater, the results can be deadly. The altered environment in diving (e.g., water that’s
  cooler than body temperature, exertion, increased partial pressures of gases) can precipitate relapses. The fact is
  the potential effects of such changes upon most medical conditions -- and the drugs used to control them -- are not
  known with certainty.  
Other readers responded along the lines of, “What does the dive op know about the implications of my medical
  issues for scuba?” The answer is, “Probably very little.” This is why the shop can quite reasonably ask you to
  report your medical status, and may require a signed clearance to dive from a physician who does understand the
  implications. Remember, if a dive crew is unaware of your medical disorders, appropriate treatment could be substantially
  delayed.  
In a related vein, some readers believed that a dive operator asking for such personal information was in violation
  of their right to medical privacy. Actually, it isn’t. The privacy provisions of the Health Insurance Portability
  and Accountability Act (HIPAA) are binding on healthcare insurers, providers and facilities, not dive operators and
  training agencies. You voluntarily waive your “right” to keep your medical information private when you contract for
  dive certification or a two-tank dive. It is the operator’s perfect right to ask the diver to be honest regarding medical
  conditions that could mean additional risks to the business, other customers and the diver himself. There is nothing
  illegal, unethical or inappropriate about this. From a liability standpoint, dive businesses would be insane not to.  
You’re not the Only Diver on the Boat 
Perhaps the lamest of the excuses was, “It’s my life and my choice to dive with a disease.” This might be arguable
  if you are an unemployed solo diver without family or friends. However, if you are diving with a dive operator and
  other customers, then your fitness to dive most assuredly is of concern to them.  
When you are less than honest in revealing your medical status, not only could you as the diver be harmed, but
  so could your buddy, divemaster or others who risk their lives to save yours. Karl Huggins, program director of
  the University of Southern California’s Catalina Hyperbaric Chamber, says that if individuals “... knowingly conceal
  these conditions once they know what the risks are, it’s not just themselves they’re putting at risk but also those who
  may need to respond to them in an emergency situation.” He goes on to say, “Divers may rationalize that ‘It’s my life
  and I can assume any risk I want because the damage I do, I do to myself.’ But when they’re paralyzed and can’t do
  their job or function normally in their work and personal lives, is it just themselves they’re affecting?”  
Not to mention that you could cause a dive trip to be aborted for everyone, possibly on an expensive liveaboard
  in a far-flung location, because the crew needs to rush you to medical care. Under these conditions, liveaboards make
  no refunds to any divers on the itinerary. If you’re lucky enough not to expire from your previously undisclosed
medical condition, you might be thrashed to death by the other passengers. 
If and when enough divers lie, incidents will occur and they eventually will catch the government’s eye. When
  that happens, laws will be passed, like requirements of medical exams before receiving dive training and mandatory
  completion of a medical history form in Australia, Malta and other locations. A number of preventable diver deaths
  due to medical reasons have occurred in Australia’s Queensland region over the past several years. Many were the
  result of divers being untruthful about their medical status and made news headlines. This resulted in the government
  considering even more rules and tighter enforcement. Do you want some random diver’s failure to disclose
  medical conditions that led to a bad dive accident or major fatality to lead to tighter restrictions on your own dives?  
You participate in recreational scuba on a voluntary basis. No one is forcing you to do it. It’s a recreational pastime,
  a fun thing to do. If you don’t like being asked to properly and truthfully complete a medical questionnaire, a
  practice intended to protect customers and the businesses that offer them scuba services, you don’t have to participate.
  You can find diversions with rules that better suit you and don’t require total disclosure of your medical history.
  Heaven knows there are dozens of them that don’t put you and others in such a potentially hazardous situation.  
- - Doc Vikingo